Zootaxa 4454 (1): 018–032 ISSN 1175-5326 (print edition) http://www.mapress.com/j/zt/ Article ZOOTAXA Copyright © 2018 Magnolia Press ISSN 1175-5334 (online edition) https://doi.org/10.11646/zootaxa.4454.1.4 http://zoobank.org/urn:lsid:zoobank.org:pub:923BFA38-A264-4E31-A606-10F7DE87B794 The freshwater snake eel genus Lamnostoma (Anguilliformes: Ophichthidae) in Taiwan, with description of a new species YUNG-CHIEH CHIU1, KWANG-TSAO SHAO2, SHIH-PIN HUANG3 & HONG-MING CHEN1,4,5 1Department of Aquaculture, National Taiwan Ocean University, Keelung 202, Taiwan 2Institute of Marine Biology, National Taiwan Ocean University, Keelung 202, Taiwan 3 Biodiversity Research Center, Academia Sinica, Taipei 115, Taiwan 4 Center of Excellence for the Oceans, National Taiwan Ocean University, Keelung 202, Taiwan 5Corresponding author. E-mail: [email protected] Abstract A review of the freshwater ophichthid eel genus Lamnostoma from Taiwan is provided with three species recognized. Lamnostoma mindora has been recorded in previous literature and its presence is confirmed. Two specimens of Lamnos- toma polyophthalmum represent the first record in Taiwan. A new species, Lamnostoma taiwanense sp. nov., is described on the basis of two specimens collected from northeastern Taiwan. It can be distinguished by having 3 preopercular pores, higher number of teeth on lower jaw, and a series of white spots with hill-shaped papillae along the head. A key to all known species of Lamnostoma is provided. Key words: Anguilliformes, Ophichthidae, Lamnostoma, new species, Taiwan Introduction Snake eels, family Ophichthidae is the most diverse family of Anguilliformes fishes, comprising about 59 genera and 319 species that are widely distributed around the tropical and subtropical water regions of the world (Nelson et al., 2016). So far, 19 genera and 60 species of ophichthid eels have been recorded in Taiwan (Ho et al., 2015; Shao, 2017). Except for Lamnostoma, ophichthid eels normally occupy various marine habitats, including intertidal wetlands, mid waters and reefs, where they burrow in sand and mud substrates. Although some species are found at depths of 1,300 m or deeper region, most usually inhabit waters with depths less than 100 m (McCosker et al., 2012). Snake eels are often caught by the bottom trawl fishery in Taiwan, and are also trapped in the estuaries area and downstream stretches of rivers. Species of Lamnostoma were collected from brackish water or in the lower reaches of rivers close to estuaries. Previous studies (Chang & Tsai, 2003, 2004) pointed out that the bottom dwelling habit of Lamnostoma mindora could be the reason why Lamnostoma species are rarely found and recorded in previous surveys. The obvious benthic preference observed in a live specimen of Lamnostoma polyophthalmum kept in an aquarium by the first author resembles the case of L. mindora reported previously (Chang & Tsai, 2004). Hatooka & Yoshino (1998) reported 2 rare ophichthid species of the genus Lamnostoma from western Pacific, including a single specimen of L. mindora collected from eastern Taiwan that was the first record of both genus and species, as well as the 4th specimen worldwide. Subsequently, Chang & Tsai (2003) presented a 5th example of L. mindora from the southwest of Taiwan, and declared that L. taylori to be a valid species; Chang & Tsai (2004) reported another 9 specimens, and provided brief ecological information. In this study we present information about 11 more specimens of L. mindora, 3 specimens of L. polyophthalmum, and 2 specimens of a new species along with additional descriptive details about these species. Currently five species of Lamnostoma are considered valid (Kottelat, 2013; van der Laan, 2016), including 18 Accepted by H.-C. Ho: 8 Jul. 2017; published: 31 Jul. 2018 Lamnostoma kampeni (Weber & de Beaufort, 1916), Lamnostoma mindora (Jordan & Richardson, 1908), Lamnostoma orientalis (McClelland, 1844), Lamnostoma polyophthalmum (Bleeker, 1853), and Lamnostoma taylori (Herre, 1923). Recently, McCosker (personal communication) who examined holotypes specimens of three of the nominal species, and concluded that L. kampeni is a junior synonym of L. mindora. In addition, L. taylori was considered to be a junior synonym of L. mindora by Hatooka & Yoshina (1998). And as a holotype was not designated in the original description of L. orientalis and the syntypes appear to have been lost, the validity of L. orientalis is controversial. The results of a taxonomic study of the genus Lamnostoma carried out in Taiwan are reported below. Two specimens of Lamnostoma polyophthalmum collected in northeastern Taiwan represent a new record for Taiwan. In addition, two specimens of Lamnostoma collected in northeastern Taiwan are described as a new species based on morphological features. Materials and methods Abbreviations and terms used in diagnosis and descriptions follow McCosker (1977) and McCosker et al. (1989), with the addition of dorsal-fin origin (DFO), anterior nostril (AN), and posterior nostril (PN). The body contains the head and trunk when comparing body and tail lengths. Counts and measurements generally follow Böhlke (1989) and McCosker et al. (1989). Measurements are straight-line and obtained with a 600 mm ruler; 1 mm gradations were used for total length (TL), tail length (Tail), trunk length (TR), head length (HL), predorsal length (PD), preanal length (PA), and distance between dorsal fin origin and upper margin of gill opening (DGW). A dial caliper, recorded to the nearest 0.1 mm, were used for body depth at gill opening (DGO), body depth at anus (DA), interorbital width (IOW), eye diameter (ED), snout length (S), ventral width between gill opening (VG; “isthmus” in Böhlke, 1989), upper jaw length (UJ), lower jaw length (LJ), and gill opening diameter (GO). Terminology of cephalic and lateral-line pores generally follows McCosker et al. (1989). Supraorbital pores (SO) are expressed as ethmoidal pore + pores in the supraorbital canal; infraorbital pores (IO) are expressed as pores along the upper jaw + those in the vertical part of the canal behind the eye (the postorbital pores), however, the last pore on the upper jaw is included as part of the postorbital pore series; the preoperculo-mandibular pores (POM) include pores on the lower jaw (mandibular pores) and preopercular canal (preopercular pores, POP, counted from the lowest and recorded as pop1, etc.); the supratemporal pores (ST) are pores on the dorsolateral side of the head pore anterior to the lateral-line pores, and the upper temporal pore (TP) from lateral view labeled as tp2 when the number of ST up to five. Frontal pore (F) is the pore on the transverse frontal commissure. Lateral-line pores (LL) are expressed as pre-gill-opening lateral-line pores (PGLL), predorsal lateral-line pores (PDLL), preanal lateral-line pores (PALL), and total lateral-line pores (TLL). Vertebral counts (hypural included) were taken from radiographs. Mean vertebral formula (MVF) follows Böhlke (1982) and is expressed as the average of predorsal vertebrae (PDV), preanal vertebrae (PAV), total vertebrae (TV). Vertebral counts when only a single specimen was available are presented as a vertebral formula (VF). Clearing and staining for studying skeletal features of lateral-line series on the head generally followed Dingerkus & Uhler (1977). All examined specimens were deposited in the collections of the Laboratory of Aquatic Ecology, Department of Aquaculture, National Taiwan Ocean University (TOU-AE) and Biodiversity Research Center, Academia Sinica, Taiwan (ASIZP). Key to species of Lamnostoma 1a. Eyes placed about 1/3 upper jaw from snout tip; gill opening lateral, anterior duplicate gill membrane absent; distance between dorsal fin origin and upper margin of gill opening 10.5–26.5% HL; no papilla on both of nostrils; 2 rows of white spots on lat- eral side of head meeting above gill opening and becoming a single row posteriorly, and forming a “Y”.. Lamnostoma mindora (Jordan & Richardson, 1908) 1b. Eyes placed near the midpoint of upper jaw; gill opening ventral, anterior duplicate gill membrane present; distance between FRESHWATER SNAKE EELS LAMNOSTOMA IN TAIWAN Zootaxa 4454 (1) © 2018 Magnolia Press · 19 dorsal fin origin and upper margin of gill opening more than 23.3% HL; both of nostrils with a slim papilla along the anterior margin; 2 rows of white spots on lateral side of head not meeting, but arranged in parallel arched rows . .2 2a. Head about 12.4–12.7% TL . Lamnostoma orientalis (McClelland, 1844) 2b. Head less than 12.4% TL . .3 3a. Ventral width between gill opening about 6.5–6.9% HL; 2 preopercular pores; 33–41 teeth on lower jaw; lateral white spots on head without hill-shaped papilla, indistinct ventrally . .Lamnostoma polyophthalmum (Bleeker, 1853) 3b. Ventral width between gill opening about 8.0–9.1% HL; 3 preopercular pores; 47–49 teeth on lower jaw; lateral white spots on head in the form of a series of hill-shaped papilla, all spots distinct . Lamnostoma taiwanense sp. nov. Taxonomy Genus Lamnostoma Kaup, 1856 Lamnostoma Kaup, 1856a: 49. Type species: L. pictum Kaup, 1856 = Dalophis orientalis McClelland, 1844 = Lamnostoma orientalis (McClelland, 1844). Anguisurus Kaup, 1856a: 24. Kaup, 1856b: 50. Type species: A. punctulatus Kaup, 1856 = Dalophis orientalis McClelland, 1844 = Lamnostoma orientalis (McClelland, 1844). Diagnosis. Body stout, cylindrical, and slightly longer than tail; vent near midpoint of TL; snout pointed and slightly slender; eye small to moderate;